A form of two-dimensional (2D) vibrational spectroscopy was used to examine the structure of a cyclic penta-peptide (cyclo-Mamb-Abu-Arg-Gly-Asp) for which both the NMR and the x-ray structures are known. Spectrally resolved cross peaks occur in the off-diagonal region of the 2D IR spectrum, analogous to those of 2D NMR of proteins and peptides. The first results have been published (Proc. Natl. Acad. Sci. USA 96, 2036 (1999)).